This application outlines an exploratory study of daily stress processes and emotional well-being among couples across the transition to parenthood. The study will longitudinally examine links between daily stressors, couple functioning, and depression/anxiety in the context of a randomized trial of an intervention previously shown to reduce maternal depression and enhance inter-parental relations. Recent investigations have enriched our understanding of the day-to-day processes through which stress disrupts physical, emotional, and mental well-being;however, the proposed study would be one of the first projects using daily diary methods to study the daily lives of couples during the transition to parenthood. This investigation is of great potential significance because the stressful period of early parenthood coincides with the period of children's greatest vulnerability and need for a warm, security- promoting family context. The findings of this study will inform a more intensive RO1 application, which will address the issues explored here in a more comprehensive and intensive manner. Such research offers the potential to yield new and important knowledge about both basic processes and intervention mechanisms that will be valuable in refining couple-level interventions. PUBLIC HEALTH RELEVANCE: This project explores the links between daily stress processes among couples and global mental health and couple relationship quality across the transition to parenthood. The transition to parenthood is a stressful period for many couples, leading to declines in levels of relationship satisfaction and increases in levels of depression and anxiety among new parents. Understanding the daily processes that contribute to these problems is an important precursor of refining prevention programs for new parents. This project will be embedded in a larger prevention trial of such a prevention program, and will also explore whether intervention impact on relationship quality and mental health is due to intervention effects on daily stress processes.